Trismus Occurrence and Link with Radiotherapy Doses in Head and Neck Cancer Patients Treated with Chemoradiotherapy

Background: Chemoradiotherapy (CRT) for head and neck cancer (HNC) induces side-effects, including trismus, which impairs quality of life by causing difficulty to eat, speak, and maintain good oral hygiene, and by altering social life. Given the wide variation of reported trismus prevalence and as a first mandatory step for the preventive physiotherapy OPEN program (NCT03979924) this study evaluated trismus occurrence and its link with radiation doses. Methods: Study population was non-larynx HNC patients with epidermoid carcinoma treated with CRT, with or without surgery. A physiotherapist measured maximal interincisal distance before, during and after CRT, at 10 weeks and 6 months. The proportion of patients with trismus (with a 95% confidence interval) was estimated. Irradiation doses were analyzed between patients with and without trismus using non-parametric Kruskal-Wallis test. Results: We included 45 patients (77.8% male), median age 61 years (range 41-77). The proportion of trismus at baseline was 24.4%, 26.8% at 10 weeks and 37.1% at 6 months. During radiotherapy, it was 27.9% at week 3 and increased to 41.9% at week 6. Trismus occurrence at 10 weeks was higher when the radiation dose to the ipsilateral lateral pterygoid muscle was above the median value, that is, 36.8 grays. Conclusion: Trismus occurrence differed according to radiation dose and cancer location. These findings highlight the necessity of early preventive physiotherapy programs to reduce trismus occurrence. The second step, of the interventional multicenter OPEN program, is currently evaluating the impact of preventive physiotherapy and patient education on trismus in a sample of 175 patients.